Here is a description of installing a Rostra Cruise Control in a Land Cruiser 78, Troopy, 2001 model with manual transmission. The procedure will be quite similar for type 60 and 80 cruisers, as well as most cars, except the electrical connections.
It might seem a bit out of place with Cruise Control on a Land Cruiser. But when you do overlanding, there is often a lot of Autobahn or motorway before you are where you want to be. Thanks to very good Touring seats in my car, the only place I get pains after days on the road is the right leg. And this is because the gas foot is kept motionless for hours and days. So when we decided to go to Mongolia, Cruise Control got high on the wish list. In southern Russia, and especially Kazakhstan, there are endless straight stretches through savanna and desert landscape.
I checked around and found an American manufacturer, Rostra, who made Cruise Controllers for the aftermarket. It had also been successfully installed in Landcruisers, and could be used on cars with manual transmission. It was ordered via Ebay and appeared after a few weeks.
Cruise Controllers are available in two main types, electric and vacuum driven. On a diesel engine there is not any good vacuum source so an electric works best. The controller consists of a servomotor and electronics in a box and a wire that is connected in parallel with the throttle wire of the car. In addition to the box there are switches to control it. Rostra has several switch types to choose from. I chose one that is installed on the steering column. For manual transmission, a switch for clutch must also be ordered. It works in the same way as the brake light switch, when you engage the clutch when shifting, the cruise control is switched off to prevent the engine from speeding. Once you have shifted you can press Resume and the controller will take over again.
The Rostra package contains everything you need and a thorough installation instructions. Everything looked professional, except for the installation instruction which could have had better drawings. But they were understandable.
On an overland car it tends to end up a lot of gadgets under the hood, so when new come in it will eventually become a space problem. On the 78 with retrofit turbo and intercooler it is quite cramped. One possibility was between the battery and the intercooler on the right side. But then the box would end up over the exhaust manifold and that is not favorable in terms of temperature. Electronics don’t like high temperature. The car is equipped with an external Trabolt oil filter. By lowering this a bit I got room for the control above it. This Trabold oil filter is by the way an interesting thing. It is a micron filter and according to the manufacturer allows you to run 50.000 km between oil changes. Don’t know if I dare to trust it, but I see that the cars from Tom’s Fahrzeugtechnik which is a renown German Land Cruiser outfitter can supply this.
Installation
Installation of the control box went smoothly with the supplied bracket after a slight modification of the bracket. Also attaching the wire to the throttle arm went smoothly, but disregard the section on putting extra beads on the wire to get slack. The servomotor will move the wire 41 mm in and out, and if the usual wire movement of the car is less than this (measured on the car’s throttle wire by giving full throttle) then slack should be applied corresponding to the difference between 41 mm and the throttle wire maximum movement.
However, as described in the assembly instructions, this will only make the wire longer. It may be necessary for some cars, but does not provide slack. Slack can be added by moving the wire sheath attachment closer to the wire’s attachment to the throttle arm. Then you get a slack in the cable.
The intake manifold on the 1hz motor has a handy threaded hole where the cable can be attached with a slight modification of the bracket provided.
Electrical connections.
Step 1: Discard all the wire splice connectors provided and solder the wires instead. Using things like this will cause problems later.
A bundle of cables must pass through the firewall. There are two connectors on the cable, and according to the installation instructions, drill a 19 mm hole for the cables. Seriously! I would like to see if anyone find room for it. So I rather cut the cables and stuck them through the existing cable-hole and soldered them inside.
Brake light and clutch switch
To get to the brake light switch and clutch, remove the ventilation duct. Connecting to the brake light switch is easy, a wire to each side of the switch. When I was going to install the clutch switch I have to say that for once I envy those with an automatic. It was a real PITA. In principle, it is easy to replace the stop bolt for the clutch pedal with a switch, just as for the brake light switch. But it is tight up there and the switch is 10 mm while the bolt is of course 8 mm. I first tried to do it with the pedal and bracket in place, and managed to get the 8mm bolt out after a couple of hours. But it is impossible to make the hole bigger with the pedal and bracket in place. Of course, I should have unscrewed the bracket right away, only a few easily accessible bolts need to be unscrewed. The bolts that attach the bracket and the clutch master I only loosened and then got the bracket bent down so I got access to the hole. I used a rotary file turbine to make the hole bigger. To drill, you probably have to take the bracket completely out, but this is no big deal.
Vehicle speed
To measure the vehicle speed, the control must be connected to the speedometer. On newer Cruisers it is not a speedometer cable, but an electronic sensor on the gearbox that generates electrical pulses. The faster you drive, the more pulses. You can connect down at the sensor, at the ECU or behind the instrument panel. On a Troopy it is very easy to remove the panel so I chose that. On an 80 it is more work to get out the panel I think I had chosen somewhere else to connect.
On older cars with speedometer cable there is a switch inside the speedometer that generates electrical pulses. I suppose it is possible to use these to measure speed. If not, an external sensor must be installed on the cable. These are available on Ebay.
Settings
For Cruisers with electronic sensor there are 4000 pulses per mile. Possibly older cars with cable speedo have the same, it seems to be the standard.
Gain(sensitivity) = Mid
Engine/SetUp Timer = 6 Cylinder / Low
VSS Source = Square Wave Input
Cruise Control test
In short, I would say it works amazingly well. As with factory-fitted cruise controls, you go to the speed you want and press the button. Then the cruise control takes over momentarily and keeps the speed very precise. The only negative is that when you brake or clutch, the cruise control switches off too abruptly so it is a jerk in the car. Here, a filter should have been inserted so that the control had released a little more gradually.
Parts
Rostra 250-1223 & 3742 Electronic Cruise Control Kit + 4206 Clutch
Switch Kit (251402052904)
